You'll be able to get the trial on the website as soon as it's available again, it's getting hammered right now. The previewer allows you to load any glsl shader. It comes with a default PBR shader and also Relief mapping and parallax shaders that uses the typical Diffuse/normal/spec/gloss outputs.
Have just created a modified version of the physically based shader for substance designer. This modified version allows you to work with a full specular map (like toolbag2, for example) instead of using the metalness workflow that the default physically based shader of SD4 uses.…